The ion milling device is a device for polishing surfaces or cross sections of metal, glass, ceramic and the like by irradiating these materials with an argon ion beam or the like, which is suitable as a pretreatment device for observing surfaces and cross sections of samples by the electron microscope such as SEM or TEM.
In the observation of cross sections of samples by the electron microscope in related art, after a portion near a portion to be observed is cut by using, for example, a diamond cutter or a jig saw, a cut surface is mechanically polished and placed on a sample stage for the electron microscope to observe an image.
In the mechanical polishing, there are problems that the surface to be observed is crashed or a deep scratch remains due to abrasive particles in soft samples such as polymeric materials or aluminum. There is also a problem that polishing is difficult in hard samples such as glass and ceramic. Moreover, there is a problem that processing of cross sections is extremely difficult in composite materials formed by stacking a soft material and a hard material.
In response to the above, the ion milling device can perform processing without crashing the surface state even in soft materials and can perform polishing of hard materials and composite materials, therefore, there is an advantage that it is possible to obtain cross sections in a mirror state easily.
As one of methods of preparing samples in such ion milling device, there is a method called cross-section milling.
In the cross-section milling, part of the ion beam is blocked by a mask (shielding plate) arranged above the sample and a cross section of the sample is sputtered along a ridge line (end surface) of the mask, and a cross section of the sample extending along the ridge line of the mask can be obtained.
It is necessary to align a position of the ridge line of the mask with a processing target position of the sample before radiation of the ion beam for performing the cross-section milling. In International Publication WO2012/060416 (Patent Literature 1), a case in which adjustment of the mask position with respect to the sample is performed by an optical microscope is disclosed.
Moreover, in JP-A-2011-249246 (Patent Literature 2), a case in which a motor, a battery and an infrared sensor are provided in a mask position adjustment mechanism, and the mask position adjustment mechanism arranged in an electron microscope is operated through an infrared lamp provided in a sample chamber is disclosed.